There is known an image recording apparatus that uses ink to record an image onto a recording sheet. This image recording apparatus includes an inkjet type recording head and is configured to selectively spray ink droplets from the recording head toward a recording sheet. The ink droplets are landed onto the recording sheet, thereby a desired image being recorded on the recording sheet. The image recording apparatus can accommodate an ink cartridge having an ink chamber that stores ink to be supplied to the recording head. The ink cartridge is detachably received in an accommodating portion provided in the image recording apparatus.
The ink cartridge to be accommodated in the image recording apparatus is internally sealed, before use, so as to prevent ink stored in the ink chamber from leaking outside. The ink chamber is brought into atmospheric pressure when used. To this end, the ink cartridge is provided with an air flow path through which the ink chamber is permitted to communicate with ambient air. Conventionally, a valve mechanism has been provided in the air flow path for opening and closing the same, for example. Japanese Patent Application Publication Nos. 2005-161641 and 2005-111922 disclose such a conventional valve system provided in the ink cartridge.